<template>
  <div>
      <router-link class="header-abs" tag="div" to="/" v-show="showAbs">
            <div class="iconfont header-abs-icon">&#xe624;</div>
      </router-link>
    <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
      <router-link to="/"> 
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      经典详情
    </div>
  </div>
</template>

<script>
export default {
  name: "DetailHeader",
  data(){
      return{
          showAbs:true,
          opacityStyle:{
            opacity:0
          }
      }
  },
  activated(){
    console.log("activated")
    window.addEventListener("scroll",this.handleScroll)
  },
  deactivated(){
    window.removeEventListener("scroll",this.handleScroll)
  },
  methods:{
    handleScroll(){
      // pc端document.documentElement.scrollTop
      console.log(document.documentElement.scrollTop)//移动端
      const top = document.documentElement.scrollTop
      if(top>60){
        let opacity = top/180
        
        opacity = opacity>1 ? 1 :opacity
        this.opacityStyle={ opacity }
        this.showAbs =false
      }else{
        this.showAbs =true
      }
    }
  }
};
</script>

<style lang="stylus" scoped>
@import "~styles/varibles.styl"
    .header-abs
        position :absolute
        left: .2rem
        top: .2rem
        width : .8rem
        height : .8rem
        line-height :.8rem
        border-radius :0.4rem
        text-align :center
        background :rgba(0,0,0,.8)
        .header-abs-icon
            color :#ffffff
            font-size :.4rem
    .header-fixed
        position: fixed
        top:0
        left :0
        right :0
        z-index :2
        height: $headerHeight
        line-height: $headerHeight
        text-align: center
        color: #fff
        background: $bgColor
        font-size: .32rem
        .header-fixed-back
            position: absolute
            top: 0
            left: 0
            width: .64rem
            text-align: center
            font-size: .4rem
            color: #fff
</style>